# Mercury 40hp Outboard



## Magnum

Ok so here is my problem. I bought a used boat and motor. The motor is a 1998 40HP Mercury. It has electric start and trim, real fancy motor. Well it did not come with any paperwork and I am trying to figure out if I need to mix the gas and If I do what ratio. It's a 2 stroke so I know it needs to be mixed, but it almost looks like it has an oil injector pump so I would just put straight gas into the tank, mix oil into the motor ( The cap says use TCW-III)

So here I am with a boat and a half tank of fuel and no idea how to fill it. The gas in the tank now is discolored, like it is mixed... or gas stabil added to it. 

Anyone have a motor like this or know where I can get some info?


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## Dutch6

http://www.capitaldistrictmarina.com/mercury_40hp2cyl_portable_clasic.htm


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## Dutch6

http://www2.shopping.com/xPO-Mercury_Mariner_Outboard_Repair_Manual_2_5_60_Hp_2_Stroke_1998_2002


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## Dupontster

You should call a Mercury dealer and maybe get a manual or some kind of informational book...That is VERY important, so you want to do it right....


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## dems4me

Magnum said:
			
		

> Ok so here is my problem. I bought a used boat and motor. The motor is a 1998 40HP Mercury. It has electric start and trim, real fancy motor. Well it did not come with any paperwork and I am trying to figure out if I need to mix the gas and If I do what ratio. It's a 2 stroke so I know it needs to be mixed, but it almost looks like it has an oil injector pump so I would just put straight gas into the tank, mix oil into the motor ( The cap says use TCW-III)
> 
> So here I am with a boat and a half tank of fuel and no idea how to fill it. The gas in the tank now is discolored, like it is mixed... or gas stabil added to it.
> 
> Anyone have a motor like this or know where I can get some info?



I called a Mercury dealer a few weeks ago with pretty much the same question, she said all Mercs that are not racing boats should be 50-1 ratio and that its been that way since I think she said 1959 I believe it was.  I was calling about a Force which is an older Mercury and I was in the clear with a 1989 on the 50-1 as well. 

A manual is also a great idea, I was able to find an old 1974 manual a few years ago on ebay. It was a miracle, but ebay had it.   Good luck! Also there's a few websites that were also helpful called oldmercs.com  and http://mercuryoutboards.com/ that should be of help!


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## mandylee

*merc outboard*

My fiance has a 14' jon with a 25 merc and his ratio is 50/1, usually 8oz of oil per 6 gallons. Check the back of the merc oil for correct ratio for 50/1.


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## Magnum

I talked to a few marine mechanics today, they all say they need to look to be totally sure but to them it sonds like I have and oil injected motor, which means I run plain gas in the tank and the motor mixes itself. I am going to try to take it down to the marina tomorrow, let them take a look.


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## wmburdette

The engine features two protection systems - a low oil level alarm and overheat warning horn - to guard against potential engine damaging situations.

The transparent window on the front cowl is a convenient feature that allows the operator to visually check the oil level in the integral oil reservoir.

Single-point oil injection, featured on all electric start models, automatically mixes the exact oil to fuel ratio for you for added convenience and ease of operation.


See Post #2 above from Dutch6.


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## Magnum

wmburdette said:
			
		

> The engine features two protection systems - a low oil level alarm and overheat warning horn - to guard against potential engine damaging situations.
> 
> The transparent window on the front cowl is a convenient feature that allows the operator to visually check the oil level in the integral oil reservoir.
> 
> Single-point oil injection, featured on all electric start models, automatically mixes the exact oil to fuel ratio for you for added convenience and ease of operation.
> 
> 
> See Post #2 above from Dutch6.


I saw that, sounds like I have me a fancy motor that mixes everything for me


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## dems4me

Magnum said:
			
		

> I saw that, sounds like I have me a fancy motor that mixes everything for me




On an outboard???? And only 40hp at that? You may definately want to check this before using pure gasoline - if you do the ratio, the worse that can happen is you run a little rich. :shrug:  Keep me posted, because I'd love to get one of these hassle free motors


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## Magnum

dems4me said:
			
		

> On an outboard???? And only 40hp at that? You may definately want to check this before using pure gasoline - if you do the ratio, the worse that can happen is you run a little rich. :shrug:  Keep me posted, because I'd love to get one of these hassle free motors


I'm pretty sure I have the oil injector, The post above has a motor but I think its not exactly the same. I am pretty sure mine is a 3 cyl, i'll have to check when I get home, and I don't think mine has the vents on the top cover. From what everyone is telling me this is a direct injection motor.


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## dems4me

Magnum said:
			
		

> I'm pretty sure I have the oil injector, The post above has a motor but I think its not exactly the same. I am pretty sure mine is a 3 cyl, i'll have to check when I get home, and I don't think mine has the vents on the top cover. From what everyone is telling me this is a direct injection motor.



That would be awesome! Goodluck


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## Magnum

Dutch6 said:
			
		

> http://www.capitaldistrictmarina.com/mercury_40hp2cyl_portable_clasic.htm


This looks like my motor for the most part, except mine is an inline 3 cylinder  

Good news is I did find a plate on the block I overlooked before. It says it has Variable oil injection. So i'm figuring that means you can adjust the ratio like the website makes it sound. So looks like I fill it up and go.


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## desertrat

Magnum said:
			
		

> This looks like my motor for the most part, except mine is an inline 3 cylinder
> 
> Good news is I did find a plate on the block I overlooked before. It says it has Variable oil injection. So i'm figuring that means you can adjust the ratio like the website makes it sound. So looks like I fill it up and go.


 VOI/VRO. Not sure about the Merc, but in a Johnson that means it is mixed in the fuel pump at the correct ratio for the speed of the motor. To be sure find your fuel pump then see how may hoses you have running to it. There would be one for fuel, one for oil and possibly one for the crankcase pressure which is used to operate the pump. One output hose goes to the carb(s). Most people that have these also mix a little oil in the gas because they don't trust them completely. Probably with good reason.


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## dems4me

Magnum said:
			
		

> Ok so here is my problem. I bought a used boat and motor. The motor is a 1998 40HP Mercury. It has electric start and trim, real fancy motor. Well it did not come with any paperwork and I am trying to figure out if I need to mix the gas and If I do what ratio. It's a 2 stroke so I know it needs to be mixed, but it almost looks like it has an oil injector pump so I would just put straight gas into the tank, mix oil into the motor ( The cap says use TCW-III)
> 
> So here I am with a boat and a half tank of fuel and no idea how to fill it. The gas in the tank now is discolored, like it is mixed... or gas stabil added to it.
> 
> Anyone have a motor like this or know where I can get some info?



A thought dawned on me about this -- why don't you just ask the guy or girl that you bought the boat from? Just mention that it didnt' come with a manual and you wanted the correct oil/gas ratio or does it automatically add the oil? :shrug:


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## Magnum

dems4me said:
			
		

> A thought dawned on me about this -- why don't you just ask the guy or girl that you bought the boat from? Just mention that it didnt' come with a manual and you wanted the correct oil/gas ratio or does it automatically add the oil? :shrug:


I tried to call and got no answer, I dont want to bug them.


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## Magnum

Well I tried to take my boat out for the first time by myself yesterday. Things did not go as planned. I went out, fired up the motor made sure the batteries were charged before I left the house. I got the boat all packed up, hooked it up to my Suburban, and off I go. I just knew I was forgetting something though. I went to stop halfway down my old back road to try to figure out what I had forgotten when all of a sudden my brake pedal goes to the floor. First time I have ever actually had to use an E brake to stop. I got out and there was a puddle of brake fluid under the truck. This is the second time I have had a brake line burst in this truck.... Starting to wonder if someone is messing with me. 

So I turned around went back home unhooked the boat and pulled the truck in the back. I guess I have a project for saturday after work now.


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## Lugnut

Magnum said:
			
		

> Well I tried to take my boat out for the first time by myself yesterday. Things did not go as planned. I went out, fired up the motor made sure the batteries were charged before I left the house. I got the boat all packed up, hooked it up to my Suburban, and off I go. I just knew I was forgetting something though. I went to stop halfway down my old back road to try to figure out what I had forgotten when all of a sudden my brake pedal goes to the floor. First time I have ever actually had to use an E brake to stop. I got out and there was a puddle of brake fluid under the truck. This is the second time I have had a brake line burst in this truck.... Starting to wonder if someone is messing with me.
> 
> So I turned around went back home unhooked the boat and pulled the truck in the back. I guess I have a project for saturday after work now.




Hey good on ya for knowing what to do and getting it stopped safely! 

What kind of brake line did you use? The stuff at haydens doesn't "feel" right when I bend it.  I buy brake line from NAPA. They carry seemless stainless steel line, already double flared.


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## Magnum

Lugnut said:
			
		

> Hey good on ya for knowing what to do and getting it stopped safely!
> 
> What kind of brake line did you use? The stuff at haydens doesn't "feel" right when I bend it.  I buy brake line from NAPA. They carry seemless stainless steel line, already double flared.


I only changed out half of the rear brake lines the first time. I had a weight proportioning distribution actuator, I just bypassed all that junk and ran new lines. I think they were aluminum. Now it's on my front brake, I didn't get under the truck to see if it's the ruber or steel line busted.


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